MIS 330 Exam #1

What are the three hardware components of a client/server system?

- Clients- The PCs that are already available on the desktops. (PCs, Macs, workstations) - Network- The cabling, communication lines, network interface cards, hubs routers and other components that connect the clients and the servers, - Server (Database Server) - A computer that has enough processor speed, internal memory (RAM), and disk storage to store the files and databases of the system.

Primary Key

A column (or set of columns) in a relation whose value is unique for each row; in case there are multiple candidates, a designer chooses one of the candidates to be the primary key.

Foreign Key

A column in a relation that refers to a primary key column in another (referred) relation.

Database System

A computer-based system whose purpose is to enable an efficient interaction between the users and the information captured in a database.

Weak Entity

A construct in an ER diagram used to depict entities that do not have unique attribute of their own.

Associative Entity

A construct used as an alternative way of depicting M:N relationships.

Composite Primary Key

A primary key that is composed of multiple attributes.

ER Diagram Shapes- *Associative Entity*

A rectangle with a diamond inside of it.

Referential Integrity Constraint

A relational database rule stating that in each row of a relation containing a foreign key, the value of the foreign key either matches one of the values in the primary key column of the referred relation or the value of the foreign key is null.

Identifying Relationship

A relationship between a weak entity and its owner entity in an ER diagram.

Binary Relationship

A relationship between two entities.

Database

A structured collection of related data stored on a computer medium.

Relation (Relational Table / Table)

A table in a relational database; contains rows and columns.

Entity-Relationship (ER) Modeling

A technique that enables the structuring and organization of the requirements collection process and provides a way to graphically represent the requirements.

Relational Schema

A visual depiction of the relational database model.

Database Management System (DBMS)

Software used for the following purposes: - Creation of databases - Insertion, storage, retrieval, update, and deletion of the data in the database - Maintenance of databases

Relational DBMS (RDBMS)

Software, based on the relational database model and used to implement relational databases.

Database Requirements

Statements that define the details and constraints of the data and metadata for the database the is being developed.

SQL

Structured Query Language, the standard language for working with a relational database. (Allows any application to communicate with any DBMS.)

Front-End Developers

In charge of creating the front-end applications.

Database Developers

In charge of implementing the database model as a functioning database using the DBMS software.

Degree of a Relationship

Indicates how many entities are involved in a relationship.

Database Designers (Database Modelers or Architects)

Involved in the database modeling stage.

Database Analysts

Involved in the requirements collection, definition, and visualization stage.

Direct Interaction

Involves the end user directly communicating with the DBMS.

Database Use

Involves the insertion, modification, deletion, and retrieval of the data contained within the database system.

Network Operating System

Manages the functions of the network.

Relationship Attributes

Many-to-many relationships can actually have attributes their own.

Entity Instances (Entity Members)

Occurrences of an entity. - Ex. Entity CUSTOMER may contain entity instances such as customer Joe.

Unary Relationship (Recursive Relationship)

Occurs when an entity is involved in a relationship with itself.

Relationship Instances

Occurs when an instance of one entity is related to an instance of another entity via a relationship.

Database Metadata

Often defined as the data about the data or the database content that is not the data itself. - Names of data structures - Data types

Types of Relationships

One-to-one Relationship (1:1) One-to-many Relationship (1:M) Many-to-many Relationship (M:N)

ER Diagram Shapes- *Attributes*

Ovals. - Ex. CustID, CustName, CustBdate, etc.

Exact Minimum and/or Maximum Cardinality

Provided so that cardinality is known in advance.

Data Access API (Application Programming Interface)

Provides the interface between the application program and the DBMS.

ER Diagram Shapes- *Entities*

Rectangles. - Ex. Customers, Store, Product, and Sale Transaction.

Enhanced ER (EER) Modeling

Refers to an expanded ER notation that depicts additional concepts beyond standard ER modeling.

Developing Front-End Applications

Refers to designing and creating applications for indirect use by the end users.

Data

Refers to facts that are recorded and can be accessed.

Front End

Refers to the client.

Database Modeling (Logical Database Modeling)

Refers to the creation of the database model that is implementable by the DBMS software.

Information

Refers to the data that is accessed by a user for some particular purpose.

Back-End

Refers to the database server.

Analytical Information

Refers to the information collected and used in support of analytical tasks.

Operational Information (Transaction Information)

Refers to the information collected and used in support of the day-to-day operational needs in a business and other organizations.

Relationship Role

Represents additional syntax that can be used in ER diagrams at the discretion of a data modeler to clarify the role of each entity in a relationship.

ER Diagram

Resulting from ER modeling, this serves as a blueprint for the database.

Aggregate Functions

SQL functions used for calculating and summarizing values in queries; includes COUNT, SUM, AVG, MIN, and MAX functions.

% Symbol

Any zero or more characters

File-Handling System

All of the processing is done on the clients. Although the clients may access data that's stored in files on the server, none of the processing is done by the server.

Conceptual Database Model

Simply a visualization of the requirements, independent of the logic on which a particular DBMS is based.

Ternary Relationship

An ER diagram relationship involving three entities; also known as a relationship of degree 3.

What are Relationships?

An ER modeling construct depicting how entities are related.

Composite Attribute

An attribute is the composed of several attributes.

Partial Key

An attribute of a weak entity that combined with the unique attribute of the owner entity uniquely identifies the weak entity's instance. - Depicted in an ER diagram by a dashed underline. - Ex. There is not unique attribute for an apartment but the apartment number is unique within the building.

Unique Attribute

An attribute whose value is different for each entity instance.

Derived Attribute

An attribute whose value will not be permanently stored in a database.

Optional Attribute

An entity attribute that is allowed to not have a value.

Composite Unique Attribute

An entity attribute that is composed of several attributes and whose value is different for each entity instance.

Owner Entity

An entity whose unique attribute provides a mechanism for identifying instances of a weak entity.

Operational Databases

Collect and present operational information in support of daily operational procedure and processes.

What are Entities?

Constructs that represent what the database keeps track of.

Front-end Applications

Created in order to provide a mechanism for easy interaction between the users and the DBMS.

Entity Integrity Constraint

In a relational table, no primary key column can have null (empty) values.

ER Diagram Shapes- *Derived Attribute*

Dashed oval line. - Ex. The current date.

ER Diagram Shapes- *Partial Key*

Dashed underline - Ex. There is not unique attribute for an apartment but the apartment number is unique within the building.

ER Diagram Shapes- *Optional Attribute*

Depicted by a capital letter O in parentheses at the end of the attribute's name. - Ex. Every employee might not be eligible for a bonus.

Attribute (of an entity)

Describes a characteristic of an entity. - Ex. For entity CUSTOMER we may keep track of CustID, CustName, CustBdate, etc.

ER Diagram Shapes- *Relationships*

Diamonds. - Ex. Reports to.

Application Software

Does the work that the user wants to do. This can be purchased or developed.

ER Diagram Shapes- *Identifying Relationship*

Double framed diamond.

ER Diagram Shapes- *Weak Entity*

Double framed rectangle.

ER Diagram Shapes- *Multivalued Attribute*

Double oval. - Ex. Keep track of multiple phone numbers.

_ Symbol

Exactly one character

Front-End Application Analysts

In charge of collecting and defining requirements for front-end applications.

Local Area Network (LAN)

The clients and the servers are local.

Metadata

The data that describes the structure and the properties of the data.

Cardinality Constraints

The lines connecting the relationship to the entities include symbols depicting how many instances of one entity can be associated with instances of another entity.

Referential Integrity Constraint Lines

The lines in a relational schema connecting the relations by pointing from the foreign keys to the corresponding primary keys.

Relational Database Model

The most commonly used logical database model; represents a database as a collection of related tables.

ER Diagram Shapes- *Unique Attribute*

The name must be underlined. - Ex. CustID.

Maximum Cardinality

The part of the cardinality constraint symbol closer to the entity rectangle.

Minimum Cardinality (Participation)

The part of the cardinality constraint symbol father away from the entity rectangle.

Client/Server System

The processing that is done by an application is typically divided between the client and the server.

Back-End Processing

The processing that's done by the DBMS.

Front-End Processing

The processing that's done by the client software.

Bridge Relation

The relation that represents an M:N relationship.

Database Administrator (DBA)

The role involves managing technical issues related to security, backup and recovery of database systems, monitoring use and adding storage as needed, and other tasks related to the proper technical functioning of the database system.

Indirect Interaction

The type of interaction between the end user and the database that involves front-end applications.

Database Deployment

This involves releasing the database system. - The database and its front-end applications, for use by the user.

Database Implementation

This involves using a DBMS to implement the database model as an actual database that is initially empty.

SQL Queries

This is how the application software communicates with the DBMS, then through the data access API. Once the DBMS receives this, it provides a service like returning the requested data to the client.

LIKE

Used for retrieval of records whose values partially match a certain criteria.

Multivalued Attribute

Used in cases where instances of an entity can have multiple values for the same attribute.

End Users (Business Users)

Users using a database system to support their work, or life, related tasks and processes.

Enterprise System

When a system consists of network, midrange system, and mainframe systems, often spread throughout the country or world.

Candidate Key

When an entity has more than one unique attribute.

Wide Area Network (WAN)

When two or more LANs reside at separate geographic locations they can be connected as part of a larger network.

SELECT *

Will select all columns.